Low frequency oscillation modes nonlinear interactions analysis using higher order spectrum non-parametric direct method

A novel algorithm for analyzing low frequency oscillation modes nonlinear interactions was proposed to avoid the disadvantages of the eigenvalue analysis method and the traditional nonlinear numerical solutions. The eigenvalue analysis method could not reveal the compound modes in oscillatory processes following large perturbations, and the traditional nonlinear numerical solutions had truncation errors and low computational efficiency. The non-parametric direct method of higher order spectrum theory was applied to analyze low frequency oscillation modes and the quadratic phase coupling information among modes were identified by using bispectrum estimation and bicoherence analysis. The nonlinear coupling degree between modes can be quantitatively calculated in this method, which provides a new way to study the stability and the dynamic behavior of power systems with strong nonlinearity. The feasibility and effectiveness of the proposed approach were verified by the numerical simulation results. © 2013 Chinese Society for Electrical Engineering.